Reaching to, and grasping visual targets is an important class of movements that requires transformations of spatial information between visual and kinesthetic coordinates. Patients with lesions of the posterior parietal cortex exhibit difficulties in reaching that are likely due to errors in visual, or kinesthetic perceptions, or in sensorimotor transformations. The proposed research involves studies of these perceptions and transformations in such patients, with a focus on lesions limited to the superior and inferior parietal cortex, and age-matched patients with occipital cortex lesions and age-matched control subjects. The Specific Aims are to determine: (1) the directions of kinesthetic coordinate axes; (2) the directions of visual coordinate axes; 3) the errors associated with sensorimotor transformations for target reaching tasks; and 4) the influence of head orientation on errors in reaching. It is suggested by the applicant that the knowledge gained from these studies should find application to the diagnosis and rehabilitation of stroke patients. A better understanding of the roles of different sensory systems and cognitive perceptions in control of reaching could lead to development of new techniques to enhance performance of upper limb movements.